With the widespread use of data processing systems affecting major aspects of an individual's personal life, as well as corporate and governmental entities, there exists an inherent risk of abuse of confidential information. Large efforts have been made in the field of information security to improve the confidentiality, integrity, and availability of information. The field of information security relates to the protection of information and information systems from unauthorized access, inspection, disclosure, recording, use, perusal, modification, disruption or destruction.
A programmable computing unit is typically designed to process a sequence of instructions to perform a certain task. The sequence of instructions may also be referred to as program code. The program code is typically stored in a memory and provided to the computing unit at runtime. With a view to information security, it may be desired to protect the instructions from being analyzed while they are stored in the memory or transmitted from the memory to the computing unit. On the other hand, errors may occur during an execution of the program code if the instructions reaching the computing unit differ from desired instructions. Differences between the instruction actually processed by the computing unit and the desired instructions may have a random cause or could be deliberately provoked by an intruder. In any event, errors caused by altered instructions should be detected early.